When the oil light comes on it's usually too late; you've already done damage. Our cars are notorious for blowing through oil and it's a good idea to check it every time you fill up. What kind of oil were you using?

As far as fixing it's going to be a major engine out type of thing. Depending on the damage you may have to start shopping for a new short block. In that case, an STi 2.5L would be a good bet, but then you're going to need to open the wallet for that. Good luck, it will work out in the end!